• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.3
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• pp.270-275
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• 2009

In a high performance motor driving system, PI controller which is simple implementation is frequently used. But, PI controller has various problems because of an integrator saturation. Therefore, the various methods of an anti-windup have been studied to solve such problems. But, conventional anti-windup methods have still problem with large overshoot and long settling time in the driving conditions. In this paper, to improve such problem, it is proposed a new anti-windup strategy. Using LPF and PI controller, it is improved an overshoot and reduced settling time. Simulation results have verified usefulness of the proposed method using MATLAB/Simulink.

• Journal of Power Electronics
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• v.15 no.1
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• pp.177-189
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• 2015

The output of the controller is said to exceed the input limits of the plant being controlled when a control system operates in a non-linear region. This process is called the windup phenomenon. The windup phenomenon is not preferable in the control system because it leads to performance degradation, such as overshoot and system instability. Many anti-windup strategies involve switching, where the integral component differently operates between the linear and the non-linear states. The range of state for the non-overshoot performance is better illustrated by the boundary integral error plane than the proportional-integral (PI) plane in windup inspection. This study proposes a PI controller with a separate closed-loop integral controller and reference value set with respect to the input command and external torque. The PI controller is compared with existing conventional proportional integral, conditional integration, tracking back calculation, and integral state prediction schemes by using ScicosLab simulations. The controller is also experimentally verified on a direct current motor under no-load and loading conditions. The proposed controller shows a promising potential with its ability to eliminate overshoot with short settling time using the decoupling mode in both conditions.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.77.1-77
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• 2001

In this paper, we propose a control scheme for improving the performance of a conventional Proportional-Integral (PI) controller for Active Queue Management (AQM) supporting TCP flows. When the PI controller is used for AQM, the windup phenomenon of the integral action causes the performance degradation. Therefore we model AQM as a system with a saturator and apply anti-windup methods to the PI controller for AQM. We compare the performances of anti-windup algorithm with the conventional PI controller through ns simulations. The simulation results show that the PI controller with anti-windup method performs better than the conventional PI controller.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.430-437
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• 2020

In this research, the anti-windup techniques for the cascade control system are newly developed. Cascade control system has an additional internal feedback control loop to reject disturbances better than the conventional control system. Remarkable difference between the conventional single-loop control system and the cascade control system is the interaction that the controller output saturation of the secondary control loop strongly affects the integral action of the primary control loop. In industry, local back calculation anti-windup method has been mainly used for each controller without considering the interaction between the two controllers. But it cannot eliminate the integral-windup of the primary controller originated from the saturation of the secondary controller output. To solve the problem, the two anti-windup techniques of the cascade conditional integration and the cascade back calculation are proposed in this research by extending the local anti-windup techniques for the single-loop control system to the cascade control system. Simulation confirmed that the proposed methods can effectively remove the integral windup of the primary controller caused by the saturation of the secondary controller output and show good control performances for various types of processes and controllers. If the reliability of the proposed methods is proved through the applications to real processes in the future, they would highly contribute to improving the control performances of the cascade control system in industry.

• Journal of Power Electronics
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• v.2 no.2
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• pp.130-138
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• 2002

The windup phenomenon appears and degrades control performance when a controller with integrating action is used and plant input is limited. An anti-windup integal-proportional(IP) controller is proposed for the variable-speed moter drives and it is experimentally applied to the speed control of a vector-controlled induction moter driven by a pulse width modulated (PWM) voltage source inverter (VSI). The consistency range of the IP controller is firstly derived and the intergal state is controlled to salisfy always the consistency range according to whether the the controller output is saturated or not. Although the operating condition like moter load or speed command is changed under the limited plant input, It is expermentally verified that the speed response has much improved performance, such as no overshoot and fast settling time, and the maximmum plant input is also effectively utilized.

• Journal of Power Electronics
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• v.11 no.1
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• pp.45-50
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• 2011

This paper proposes a method for comparing and evaluating anti-windup proportional-integral (PI) control strategies. The so-called PI plane is used and its coordinate is composed of the error and the integral state. In addition, an anti-windup PI controller with integral state prediction is proposed. The anti-windup scheme can be easily analyzed and evaluated on the PI plane in detail. Representative anti-windup methods are experimentally applied to the speed control of a vector-controlled induction motor driven by a pulse width modulated (PWM) voltage-source inverter (VSI). The experimental results compare the anti-windup PI controllers. It is empathized that the initial value of the integral state at the beginning of the linear range dominates the control performance in terms of overshoot and settling time.

• Journal of Ocean Engineering and Technology
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• v.16 no.4
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• pp.61-69
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• 2002

In the actual control systems, there exist many kinds of restrictions or nonlinearities. However, due to the nonlinearities in actuators and sensors, the designed controller may not be applicable in some practical situations. One such nonlinearity is amplitude saturation in actuators. Although sometimes it may be ignored, in other cases failure to consider actuator saturation may severely degrade closed-loop system performance and even lead to instability. On the other hand, limiting the controller gain to avoid saturation sacrifices control effort and may lead to loss of performance. Consequently, in some cases, the actuator saturation must be explicitly taken into account to ensure desired performance. However, in this paper, an anti-windup control system design method is introduced to suppress the windup due to the amplitude saturation of the actuator. The proposed control system has very simple design process and guarantees the good control performance. The validity of the proposed control system will be shown by comparing with the results of a reported paper.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.6
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• pp.33-39
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• 2007

In this paper, novel topology for fast response of various loads is proposed. The windup phenomenon appears and results in performance degradation when the PI controller output is saturated. A new anti-windup PI controller is proposed to improve the control performance of variable speed motor drives, and it is experimentally applied to the speed control of a hysteresis current-controlled SRM driven by an asymmetry bridge converter. The experimental results show that the speed response has much improved performance, such as small overshoot and fast settling time, over the conventional PI control.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.2
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• pp.128-136
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• 2003

This paper investigates the application of the anti-windup scheme to control U voltage of the three-phase four-wire active power filter, installed in a three-phase four-wire power system. In order to reduce efficiently the harmonic currents caused by the switching loads and to improve the whole performance of the flower system, the DC voltage of the three-phase four-wire active power filter should be properly controlled. PI controller can be applied to the U voltage controller of the three-phase four-wire active power filter. However, a large error input to PI controller leads to a windup phenomenon which deteriorate the dynamic characteristics of the U voltage controller Therefore, the application of the anti-windup scheme for the DC voltage controller is proposed and the improved performances of the anti-windup U voltage controller are proved through the computer simulation study.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.127-127
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• 2000

The anti-windup schemes developed so far are summarized and the similarities/differences schemes are discussed. The anti-windup schemes are applied to a DC servomotor control system with PID controller to perform comparative study and sensitivity analysis. Based on those results, some criteria for choosing anti-windup scheme are suggested. The results of this study provide a very useful guideline for selecting and designing the anti-windup scheme for various types of PID control systems.